First to see the quality on the photon map you should enable the "show radiance map" setting to see whether there is a homogeneous distribution of indirect lighting across the scene, without black patches.You have more information about photon mapping below:https://docs.google.com/document/d/1OZF ... sp=sharing

Secondly, the white fireflies are probably produced not by photon mapping but by the direct lighting integrator sampling one of the light sources which is too close to a mesh, either the light sources on the wall or the ones into the lamp. This is a known difficult case for raytracers and the only way to solve it is with more AA sampling and light samples.

There is a clay render feature that you should enable as well with "show radiance map" to see the quality of the photon map without material colors interference. Anyway the photon map you show is already good.

Radius is related to scene units, if in your scene 1 blender unit = 1 meter, this would mean that radius=0.01 is in fact radius = 1 cm., which is too much for photon mapping and will require a lot of photons. In interior scenes with that configuration I usually work with radius = 0.10 or 0.15

I needed to make a wood material, and habitually (having some expr. with Cycles) used the diffused material. In the picture I positioned mesh lights against the bannisters, corbels and walls, to show the reflections (in the upper part, on the curved moulding, there are many of them).

Samo already recommended to use Glossy, and it worked (second picture). But in it's current version glossy looks a little bit different. It would be nice to have a choice btw diffuse and glossy for such situations.

Photon mapping only calculates indirect lighting contribution. Final gather is basically a path tracing algorithm limited to one bounce that interpolates photonmapping results, but it produces montecarlo noise which is bad for detail. You need FG more samples to get rid of noise.